Microdispensing device

ABSTRACT

THIS INVENTION IS A MICRODISPENSING DEVICE INTO WHICH A PRECISION AMOUNT OF LIQUID MAY BE DRAWN AND DISPENSED. THE DEVICE INCLUDES A BARREL HAVING A BORE AND A DISPOSABLE CAPILLARY TUBE REMOVABLY HELD IN COMMUNICATION WITH ONE TERMINAL OF THE BORE. A PLUNGER MOVES THROUGH THE BARREL AND THE CAPILLARY TUBE, THE PLUNGER EXTENDING THROUGH AN END CAP IN THE OPPOSITE TERMINAL OF THE BARREL. UNIFORMLY SPACED ANNULAR RECESSES IN THE OUTER PERIPHERY OF A PLUNGER HOLDER SELECTIVELY ENGAGE A WIRE SPRING DETENT FOR DETERMINING BY &#34;FEEL&#34; THE AMOUNT OF LIQUID DISPENSED. TRAVEL LIMITING INSERTS REMOVABLY POSITIONED IN THE BARREL REGULATE THE LENGTH OF THE PLUNGER STROKE AND CONSEQUENTLY THE AMOUNT OF LIQUID DRAWN INTO AND DISPENSED FROM THE DEVICE.

y 29, 1973 M. E. DRUMMOND ETAL 27.545

MICRODISPENSING DEVICE 2 Sheets-Sheet 1 Original Filed Nov. 10, 1969 May29., 1973 M E, DRUMMOND ETAL Re. 27,645

MICRODISPENSING DEVICE Original Filed Nov. 10, 1969 2 Sheets-Sheet 11NVENTOR.S

Michael E. Drummond John E. Robinson United States Patent Oflice Re.27,645 Reissued May 29, 1973 27,645 MICRODISPENSING DEVICE Michael E.Drummond, West Chester, and John E. Robinson, Springfield, Pa.,assignors to Drummond Instrument Co., Broomall, Pa.

Original No. 3,606,086, dated Sept. 20, 1971, Ser. No. 875,082, Nov. 10,1969. Application for reissue Feb. 11, 1972, Ser. No. 225,683

Int. Cl. B67d /22 US. Cl. 222-49 12 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE Uniformly spaced annular recesses in theouter periphery of a plunger holder selectively engage a wire springdetent for determining by feel the amount of liquid dispensed. Travellimiting inserts removably positioned in the barrel regulate the lengthof the plunger stroke and consequently the amount of liquid drawn intoand dispensed from the device.

OBJECTS AND DESCRIPTION OF FIGURES OF DRAWINGS It is an object of thisinvention to provide a microdispensing device into which small,accurately measured amounts of liquid are drawn, and subsequentlydispensed therefrom.

Another object is to provide a microdispensing device which includes abarrel holding a capillary tube through which a plunger operates, todraw liquid into, and dispense liquid from, the capillary tube. Theplunger is connected to a plunger holder having a plurality ofgraduations in the form of annular recesses engaged by a detent carriedby the barrel as the plunger holder and plunger move through the barrel,for indicating to the user by feel, the exact quantity of liquid whichhas been drawn into or dispensed from, the device.

A further object is to provide a microdispensing device wherein thecapillary tube is removably inserted into the barrel for readyreplacement, a portion of the barrel being cut-away to afford a visualindication that the tube is properly seated in the barrel, the devicebeing further provided with means for holding the tube in seatedposition.

A still further object is to provide a microdispensing device of thecharacter described, with the addition of barrel inserts of differentsizes selectively inserted into the barrel for regulating the length ofthe stroke of the plunger and plunger holder, thereby limiting thequantity of liquid drawn into and dispensed by the device.

Other objects will be manifest from the following description of thepresently preferred form of the present invention, taken in conjunctionwith the appended drawing, wherein FIG. 1 is a side elevational view ofthe microdispensing device of the present invention;

FIG. 2 is an end elevational view of the same;

FIG. 3 is a longitudinal sectional view taken along the line 3-3 of FIG.1, looking in the direction of the arrows;

FIG. 4 is a cross-sectional view taken along the line 44 of FIG. 3,looking in the direction of the arrows; FIG. 5 is a cross-sectional viewtaken along the line 5-5 of FIG. 3, looking in the direction of thearrows; FIG. 6 is a perspective view of a barrel insert, forming a partof the present invention;

FIG. 7 is a view similar to FIG. 6, illustrating a barrel insert ofdifferent size, and

FIG. 8 is a fragmentary sectional view similar to FIG. 3, showing abarrel insert in position DETAILED DESCRIPTION OF INVENTION Themicrodispensing device of the present invention includes a cylindricalbarrel 20 having an axial bore 22 in which is located a convolute spring24.

An end cap 26 is provided with a central reduced extension 28 which isthreadably engaged with the internal wall of barrel 20, as indicated at30, for permitting positioning and removal of the end cap.

The opposite end of barrel 20 is closed by a wall 32, the centralforward portion of which is extended as indicated at 34. Extension 34 isof cylindrical shape, the outer periphery of which is threaded at 36 forengagement with a collet 38. Au O-ring is indicated at 39.

In accordance with the present invention, and as shown to advantage inFIG. 3, a disposable glass capillary tube 40 of predetermined length isinserted through the central aperture of coliet 38, through O-ring 39and through an axial opening in extension 34 and wall 32. At a pointadjacent, but spaced from axial bore 22, a semi-circular segment of wall32 is cut-away as indicated at 42, the cutaway section extending fromthe outer periphery of the wall to a point just beyond the axial bore ofthe wall.

A thin wall 44 between the cut-away section and bore 22 serves as anabutment for properly seating capillary tube 40. Wall 44 is furtherprovided with an axial bore 46 which is of reduced cross-sectional areain order to prevent passage of capillary tube 40 therethrough.

Tube 40 is fixedly held in position by collet 38 during the filling anddispensing operation. When it is desired to remove tube 40 for disposaland replacement, collet 38 is unscrewed from extension 34, therebypermitting the tube to be moved longitudinally through the axial openingin extension 34 and wall 32.

It is further within the contemplation of the present invention toprovide a plunger 48 which is preferably of stainless steelconstruction, the cross-sectional area of which is approximately equalto the cross-sectional area of the bore of capillary tube 40, in orderto permit passage of plunger 48 therelhrough in a manner to expel liquidin advance thereof from the tube. The crosssectional area of the plungeris also approximately equal to the cross-sectional area of the bore 46of wall 44 to allow communication of the plunger with the bore of thecapillary tube.

The inner terminal of plunger 48 is held by a plunger holder 50 ofcylindrical shape, the plunger extending into an axial recess located atthe inner terminal of the plunger holder, and removably held by a setscrew 52.

It will be noted from a consideration of FIG. 3, that plunger holder 50is of uniform diameter throughout a substantial portion of its lengthand extends through a bore in end cap 26 and central extension 28.Inwardly of barrel 20, and slightly spaced from the inner terminal ofplunger 48, holder 50 is provided with an annular enlargement comprisinga stop 56 beyond which the plunger holder is extended at 58.

As shown in FIG. 3, one terminal of coil spring 24 is in contiguousengagement with the outer periphery of extension 58, the rearwardmovement of spring 24 being limited by engagement with stop 56 whichextends between the main body portion of plunger 48 and the inner wallof barrel 20. By means of this structure, spring 24 urges plunger holder50 in an outward direction in a well known manner.

Plunger holder 50 is further provided with a series of gt aduationscomprising uniformly spaced annular recesses 60, 61 and 62 which arenormally beyond cap 26 externally of barrel 20. In co-operation withannular recesses 60, 61 and 62, end cap 26 is provided with an exteriordetent, as shown in FIG. 2, the detent including a round wire spring 64,one terminal of which is coiled around a retaining screw 66. Wire spring64 extends across a substantial portion of end cap 26 and, as shown inFIGS. 2 and 3, is so located that the wire spring engages annularrecesses 60, 61 and 62 as plunger holder 50 reciprocates back and forththrough end cap 26.

The device of the present invention is so constructed that when plunger48 and plunger holder 50 are urged under finger pressure through bore 22of barrel 2!] and capillary tube 40 against the tension of spring 24,and when the outer terminal of plunger holder 50 is uniplanar with theouter planar surface of end cap 26, then the opposite terminal ofplunger 48 protrudes approximately one-sixteenth of an inch beyondcapillary tube 40. This insures complete delivery of the liquid samplefrom capillary tube 40. even when plunger holder 50 sinks slightly intothe flesh of the finger tip, preventing the terminal of the holder fromlying coplanar with end cap 26.

As fiuid is drawn into the capillary tube by permitting the tension ofcoil spring 24 to reverse the direction of movement of the plunger andplunger holder, then liquid is drawn into tube 40. As spring detent 64engages annular recess 60, the user of the device *feels the contact ofthe spring and recess, and is immediately advised that a specifiedamount of liquid, e.g., one microliter, has been drawn into capillarytube 40. In like manner, the user is also advised when the spring detent64 engages recesses 61 and 62 that additional quantities of liquid havebeen drawn into the capillary tube, e.g. two microliters and threemicroliters.

It is also a salient part of the present invention to provide means forlimiting the length of the stroke of plunger 48 and plunger holder 50.These inserts comprise cylindrical sleeves 68 and 70 which are adaptedto be selectively placed within axial bore 22 of barrel 20.

As shown in FIG. 8, insert 68, for example, may be inserted into bore 22by first removing end cap 26 and then fitting the insert over the bodyof plunger holder 50. The insert is slid along the body of the plungerholder until the inner terminal thereof engages stop 56. End cap 26 isnext threaded into bore 20, the extension portion 28 engaging theoutermost terminal of the insert, thereby forcing the insert and plungerholder inwardly against the tension of spring 24.

As shown to advantage in FIG. 8, the length of the stroke of plungerholder 50 and plunger 48 is thereby limited, so that upon fulldepression of the plunger holder, a lesser amount of liquid is drawninto the capillary tube 40 with the end cylindrical insert which isshown in FIG. 8, only one microliter of liquid is drawn into thecapillary tube, and with the cylindrical insert shown in FIG. 7, twomicroliters of liquid is drawn into the capillary tube. Various sizes ofinserts may of course be employed to regulate the maximum amount ofliquid which may be drawn into a capillary tube.

While the invention has been described, it will be understood that it iscapable of further modifications and this application is intended tocover any variations, uses, or adaptations of the invention following ingeneral, the principles of the invention and including such departuresfrom the present disclosure as come' Within known ar customary practicein the art to which the invention pertains, and as may be applied to theessential features hereinbefore set forth and as fall within the scopeof the invention or the limits of the appended claims.

What we claim is:

1. A microdispcnsing device comprising:

(a) a barrel having a cap at one terminal thereof,

(b) tube means inserted into the opposite terminal of said barrel,

(c) a plunger movable through said barrel and said tube means fordrawing liquid into and dispensing liquid from said tube means,

(d) a plunger holder fixed to one terminal of said plunger,

(c) said plunger holder extending through said cap and being providedwith annular recesses,

(f) detent means mounted on said cap for engagement with the annularrecesses of said plunger holder,

(g) whereby upon movement of said plunger, and plunger rod through saidcap, said detent means selectively engages the annular recesses of saidplunger holder in order that the user may feel" when a predeterminedamount of liquid has been drawn into, or dispensed from, said tubemeans,

(h) spring means within said barrel for biasing said plunger holderoutwardly of said barrel, and

(i) an insert removably positioned within said barrel, for limiting thestroke of said plunger rod and thereby regulate the amount of liquiddrawn into, and dispensed from said tube means.

2. A microdispensing device comprising:

(a) a barrel having a cap at the rear thereof,

(b) a plunger extending through said barrel,

(c) a plunger holder engaged with a terminal of said plunger, a portionof said plunger holder extending through said cap,

(d) the opposite end of said barrel having a wall,

(e) an axial bore extending through said barrel,

(l) a segment of said wall being cut away from the outer periphery tothe axial bore,

(g) the axial bore in said wall rearwardly of the cutaway segment beingof reduced diameter for the reception of said plunger,

(h) tube means for insertion through the axial bore of the forwardportion of said wall and through the cut-away portion of the barrel,

(i) the inner terminal of said tube means abutting against that portionof the wall adjacent the cutaway segment, having an axial bore ofreduced diameter,

(j) whereby visual indication of the proper seating of said tube meansin said barrel is afiorded, and

(k) means for holding said tube means in position within said barrel.

3. The microdispensing device of claim 2, wherein said means for holdingsaid tube means in position within the barrel includes:

(a) a collet threadedly engaged with the forward extremity of saidbarrel,

(b) said collet being in retaining engagement with said tube means.

4. A microdispensing device including:

(a) a barrel having an axial bore,

(b) a cap covering one end of said barrel,

(c) a wall at the opposite end of said barrel,

(d) a wall at the opposite end of said barrel,

(d) the forward portion of said wall being provided with a reduced axialbore of the forward portion of said wall.

(e) a capillary tube inserted through the reduced axial bore of theforward portion of said wall,

(f) a portion of said wall being cut away from the outer periphery ofthe wall to the axial bore thereof,

(g) the remaining portion of said wall being further reduced in size toprevent the passage of said capillary tube therethrough,

(h) whereby visual indication is afforded of the proper seating of saidcapillary tube,

(i) a plunger extending axially through said barrel into said capillarytube,

(i) plunger holder connected to the rear terminal of said plunger,

(k) said plunger holder extending through said cap,

and

(1) means for normally biasing said plunger and plunger holder in arearward direction.

5. The microdispensing device of claim 4, wherein:

(a) the outer portion of said plunger holder is provided with aplurality of spaced annular recesses comprising graduations, and

(b) a spring detent carried by said cap for engagement with the annularrecesses of said plunger holder,

(c) whereby the user can feel when a predetermined amount of liquid hasbeen drawn into or expelled from, said capillary tube.

6. The microdispensing device of claim 5, with the Idition of:

(a) inserts of different length selectively placed in said barrelbetween the terminal of said plunger holder and said cap, to limit thethrow of said plunger and plunger holder, and the amount of liquid drawninto, and dispensed from, said capillary tube.

7. A microdispensing device comprising:

(a) a barrel having a cap at one terminal thereof,

(b) tube means inserted into the opposite terminal of said barrel,

(c) a plunger movable through said barrel and said tube means fordrawing liquid into and dispensing liquid from said tube means,

(d) a plunger holder fixed to one terminal of said plunger,

(e) said plunger holder extending through said cap and being providedwith annular recesses. and

(f) detent means mounted on said cap for engagement with the annularrecesses of said plunger holder,

(g) whereby upon movement of said plunger, and plunger rod through saidcap, said detent means selectively engages the annular recesses of saidplunger holder in order that the user may feel when a predeterminedamount of liquid has been drawn into, or dispensed from, said tubemeans,

(b) said barrel including a wall at the front end thereof,

(i) an axial bore in said wall,

(j) a portion of said wall being cut away from the outer peripheryinwardly to the longitudinal axis of said wall,

(k) the axial bore in the forward portion of said wall being of adiameter to permit passage of said tube means therethrough,

(l) the size of the axial bore being reduced beyond the cut-away portionof the wall to permit passage of said plunger through the wall into saidtube means while preventing rearward movement of said tube means beyondthe cut-away portion of the wall,

(m) whereby visual indication is aiforded of the proper location of saidtube means.

8. The microdispensing device of claim 7, with the addition of:

(a) an extension protruding forwardly of said wall,

and

(b) a collet threadedly engaged with said extension,

(c) said collet being in retaining engagement with said tube means.

9. A microdispensing device comprising:

(a) a barrel having a cap at one terminal thereof,

(b) tube means inserted into the opposite terminal of said barrel,

(c) a plunger movable through said barrel and said tube means fordrawing liquid into and dispensing liquid from said tube means,

(d) a plunger holder fixed to one terminal of said plunger,

(c) said plunger holder extending through said cap [and being providedwith annular recesses], and (f) an insert removably positioned with saidbarrel,

for limiting the stroke of said plunger rod and thereby regulate theamount of liquid drawn into, and

dispensed from, said tube means.

10. The microdispensing device of claim 9, with the addition of:

(a) inserts of different lengths selectively placed in said barrelbetween the terminal of said plunger holder and said cap, to limit thethrow of said plunger and plunger holder, and the amount of liquid drawninto, and dispensed from, said capillary tube.

11. The microdispensing device of claim 9, wherein:

(a) said barrel includes a wall at the front end thereof,

(b) an axial bore in said wall,

(c) a portion of said wall being cut-away from the outer peripheryinwardly to the longitudinal axis of said wall,

(d) the axial bore in the forward portion of said wall being of adiameter to permit passage of said tube means therethrough,

(e) the size of the axial bore being reduced beyond the cut-away portionof the wall to permit passage of said plunger through the wall into saidtube means while preventing rearward movement of said tublela meansbeyond the cut-away portion of the wa (f) whereby visual indication isalforded of the proper location of said tube means.

12. The microdispensing device of claim 11, with the addition of:

(a) an extension protruding forwardly of said wall,

(b) a collet threadedly engaged with said extension,

(c) said collet being in retaining engagement with said tube means.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 197,017 11/1877 Colmer 222-309 X 2,373,520 4/1945Wallin 128-218 C 2,474,496 6/1949 Rayman 128-218 C 2,530,909 11/1950Riggs 222309 X 2,558,998 7/1951 Yearout 222-49 2,943,624 7/1960 Alquist128-218 C 3,101,084 8/1963 Hamilton 128-218 C 1,393,720 10/1921 Lamos etal. 128-234 2,128,254 8/1938 Kile 222-309 3,343,539 9/1967 Moorhouse128-234 2,875,761 3/1959 Helmer et al. 128-218 C FOREIGN PATENTS 603,7018/1960 Canada 222-309 M. HENSON, WOOD, 111., Primary Examiner E. D.GRANT, Assistant Examiner U.S. Cl. X.R.

